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I raised the CL to 3ppm. Didn't get a chance to lower the water level. Yesterday evening I was able to get out there and test and vacuum. My test results were:

FC- 1.0
CC- .5
pH- 7.2-7.3
TA- 100
CH- 180
CYA- still 20 ish

There were some green patches on the bottom. I vacuumed to waste ( the tip for doing it with cartridge filters works like a charm!) and got the loose algae up and water level down some. I noticed that the liner is now bleached up to where the water was at the top of the skimmer. I added a gallon of 12.5% to shock it and did some brushing. This morning when I tested the CL it was:

FC- 13
CC- 0

Any idea what is bleaching the liner? I know the CYA is still low and the pH is at the lower end of the range, but I thought it was high enough to prevent bleaching.

Liners will bleach below the water line with age, but this takes many years. To bleach a liner quickly you need very very high chlorine levels or normally high chlorine levels and absolutely no CYA. There is some possibility that very very low PH might bleach the liner as well, thought that is being debated.

Based on the numbers you posted, I see nothing that would fade your liner. My best guess is that it may have been there before and you just noticed it with the extra attention you've been giving the pool. Is that possible?

Typically, pH low or high should have no affect on the color of your liner. 30+chlorine levels are when bleacing problems can occur and it sounds like you've never been that high.

As an aside, I would do little to adjust your pH for a while....it may come up on it's own and it's not bad now.

heatmisr,
How long have you been using liquid chlorine? Does the fading go all the way around, or is it a localized area? How have you physically been adding liquid chlorine to the pool ... pouring into the skimmer, or near the sides, etc?

It isn't age because the pool is only 2 years old. I don't know what the previous owner did, but there are a couple huge bleached out spots on the bottom. They are almost white. The bleaching around the sides is definitely new. We thought the previous "water line" on the liner at normal water level was just part of the liner. (It's nothing special, plain blue on the sides) Now I know it isn't because it is now bleached up to the top of the skimmer where the water level was the past 2 days.

I have a feeling this liner is not going to last too long. The bottom of the pool has some dips in it and there are quite a few creases in the liner also.

Thanks for the suggestion about the pH because I was going to try to bump it up a bit.

heatmisr,
How long have you been using liquid chlorine? Does the fading go all the way around, or is it a localized area? How have you physically been adding liquid chlorine to the pool ... pouring into the skimmer, or near the sides, etc?

I have been using it since I started my algae odyssey about 2 1/2 weeks ago. The fading goes all the way around. We were using the line that was mid-skimmer level as a water line marker. I have added it all the way around the sides and also through the skimmer. I have been adding it through the skimmer for the last week. I add a little, let it circulate and add some more.

I would guess that the previous owner may have used Cal-Hypo, possibly for shocking, and dumped it into the pool rather than pre-diluting or mixing it. Cal-Hypo doesn't dissolve quickly so sank to the bottom where the high chlorine level bleached the liner, especially because in an above-ground pool there is generally no floor drain so poor circulation at the bottom.

You also don't want to add bleach or chlorinating liquid quickly in one place either. It is denser than water and if not mixed it can sink to the bottom. Adding it slowly over a return and mixing things up with a brush afterwards help dilute the chlorine faster (some pour it slowly into the skimmer, but I think pouring into a larger body of water is better, so long as it gets mixed).

I would guess that the previous owner may have used Cal-Hypo, possibly for shocking, and dumped it into the pool rather than pre-diluting or mixing it. Cal-Hypo doesn't dissolve quickly so sank to the bottom where the high chlorine level bleached the liner, especially because in an above-ground pool there is generally no floor drain so poor circulation at the bottom.

You also don't want to add bleach or chlorinating liquid quickly in one place either. It is denser than water and if not mixed it can sink to the bottom. Adding it slowly over a return and mixing things up with a brush afterwards help dilute the chlorine faster (some pour it slowly into the skimmer, but I think pouring into a larger body of water is better, so long as it gets mixed).

I don't know what would cause the bleaching at the waterline.

Richard

Richard,

I thought the same thing about the bleaching on the bottom, except it is in the middle of the pool. Something was definitely sitting there for a while, just haven't figured out what. I mean, what are the chances of being able to dump an entire bag of shock into the middle of a 21' round? I thought maybe he through a couple of pucks in there because that is what he was using for chlorination.

Ok, I thought it would mix better if I put it through the skimmer, but I guess I can go back to broadcasting it around the perimeter. But at 5'1" and a 52" pool, I have messed up a few shirts and bras from the bleach splash back....lol.

Wolf,

I don't know about the cleaning thing because the previous owner was using a CL system. The difference in the color is like comparing a medium blue with a lighter blue. Noticiable, but not horrible. Looking at this post, if the color scheme is blue for you, the original color is the color of the scroll bar and the new color is the background color of the quote box.

Don't change your method so long as you add the chlorine slowly. I was just giving you my preference and it's not around the perimeter -- it's only way over the edge into the water flow stream from the return with the pump running. In my own pool, I do it at the deep end, but that's because I have a floor drain so the flow goes from return jet dispersion into a large body of water and diluted into the skimmer opposite and floor drain below -- that's the pattern blue dye took when I did a circulation test (you can use GLB Party Blue to check your circulation -- it's fun, too, and goes away in a couple of days). The chlorine through a skimmer does distribute well but when I do calculations I find that with normal GPM flows even adding slowly to a skimmer is still a rather high chlorine level -- it might not be a problem, but I just figured having it dilute more quickly into a large volume with vigorous circulation from the return would be best.

Yes, perhaps he threw in Trichlor pucks. Those aren't just concentrated chlorine, but are highly acidic so that combination would clearly be horrible -- but I would expect the bleached area to be on the order of 3" puck sizes or thereabouts while it sounded like they were much bigger than that.

I am not sure if this will help or not, but I know a soft sided pool we had at our Cottage, I did exactly what you are seeing. I had no idea about pool chemistry or anything else, but I had algae, and yep...threw three pucks into it as I had no other way, well, 7 days later, YIKES...totally bleached out the spots to complete white. 1 year later, those spots were so brittle they eventually started leaking. I am with Richard, the previous owner was unsure of what to do, and threw something in the water that settled to the bottom.

I think for me, in the skimmer may be the best bet. I'm only 9" taller than my pool walls, so I can't get it too far into the pool pouring it over the side. I do make sure I pour it slowly and not all at one time so it has a chance to move through the water. I always make sure the pump is running when I add the bleach so it does have a chance to circulate.

I don't know what he did, but I am sure it wasn't done properly. We have run into a lot of things that haven't been done properly in this house. I am starting to suspect that he excavated and installed this pool himself. He did a lot of other things in the house himself and he cut corners on a lot of them while he was doing it. I just hope this liner lasts another year or 2. We have put a lot of money and effort into making this pool usable and would like to enjoy a season or 2 before having to undertake something so major.

The bleached out spots on the bottom of the pool are definitely brittle. Stepping on them feels like stepping on uneven concrete. There are also a LOT of uneven areas, almost like footprints, and a couple of huge creases. I know now he definitely did this himself because I would not pay a professional to do an install like that.

I mean, what are the chances of being able to dump an entire bag of shock into the middle of a 21' round?

It could easily migrate there. See the thread about "whirlpooling".

I agree. I have a family member that does the whirlpool technique, and also runs the pump on a timer. So the chlorine could settle to the middle especially if the pump isn't running. That's what happened to their's.